Hereinbefore, against a disease caused by a crystalline lens, such as cataract, a remedial method by an intraocular lens and a contact lens has been adopted. However, while a natural crystalline lens has a property that an ultraviolet (UV) ray and visible lights in a blue range of about 380 to 500 nm are not transmitted, a polymethyl methacrylate, etc. which has conventionally most widely been used as a lens material can transmit visible lights and an UV ray, and thus there has been such a problem that wearing an ophthalmic lens made of this material causes dazzling and bluish sight as compared with a natural eye. Further, it has been considered that retina is damaged by using a conventional lens material permeating an UV ray.
Hereinbefore, as a material for an ophthalmic lens having absorption property of an UV ray and visible lights having specific wave length range (about 380 to 500 nm), a benzophenone type polymerizable UV-absorbable dye has been known (Japanese Patent Publication No. H2-232056A). Specifically, the compound has been obtained by reacting 2,4-dihydroxy-5-(4-(2-hydroxyethyl)phenylazo) benzophenone (UV-PEP) and the like with a compound having a polymerizable group such as methacryloyl chloride. However, the pigment disclosed in Japanese Patent Publication No. H2-232056A contains no urethane group, and thus when it is used in a large amount in a foldable intraocular lens made of a soft acrylic acid resin (hereinafter referred to as a soft foldable intraocular lens), there have been observed such problems that the implant becomes hard and the function of the said intraocular lens of inserting into an eye under bending is prohibited or lowered.
Further, when UV-PEP is reacted with methacrylic acid according to the disclosure of the patent publication, such a problem has been accompanied that a product produced by reacting with a phenolic hydroxyl group is produced as well as the desired product produced by reacting with a primary hydroxyl group, because UV-PEP contains one primary hydroxyl group and two phenolic hydroxyl groups, and thus yield of the desired product is reduced remarkably, and production in an industrial scale is very difficult because of difficulty in separation and purification.